Multiple electric heater assembly



Jan. 15, 1957 G. GLENN MULTIPLE ELECTRIC HEATER ASSEMBLY Original Filed April 1, 1955 IN V EN TOR.

/RV/NG G. GLENN A 7' TORNE) United States Patent MULTIPLE ELECTRIC HEATER ASSEMBLY Irving G. Glenn, New York, N. Y.

Application September 30, 1955, Serial No. 537,868

6 Claims. (Cl. 201-67) This invention relates generally to variable electric heating units and more particularly to the form and material of the elements employed that make up a unit. Further, to relatively positioning such elements, to produce a rigid unit assembly, preliminary to final pressure processing the same, which results in imparting unlimited flexibility to the unit, adapting it to be bent cold, to any form desired, to meet any and all structural use requirements without impairing the effectiveness of the unit in operation.

This invention is a division of my prior application, Serial No. 346,137, filed April 1, 1953, now Patent No. 2,721,247, entitled Multiple Electric Heater Assembly.

The object of the invention is, broadly, to provide, in a single flexible sheathed unit, of minimized cross section, means for obtaining better electric heat control, such for example, as three phase, when desired or, by switching to series or multiple, high, low and other heat variations.

A further object is to simplify and facilitate assembly and insure uniform distribution and maintenance of effective insulation against hot spots, shorts or burn-outs, particularly when the unit is bent cold on short radius, for which it is flexibly adapted.

In the preferred embodiment of the invention, the heating elements are fitted snugly, individually, in a preformed one piece multitubular insulator, of chalky porcelain or like frangible material which, as preformed, is of maximum cross sectional dimensions obtained in its use.

The preformed tubular insulator is externally ribbed lengthwise and when the heater elements and insulator assembly is entered in the metallic sheath, it is centered therein and fills the greater portion of the bore thereof, the ribs of the insulator making fairly close contact with the bore.

With the essential elements of the unit assembled, as described, the remaining unoccupied space within the sheath, is filled with powdered or granular insulating material, such as magnesite or the like and, after the sheath is sealed about the projecting terminals of the heating elements, in a conventional manner, the unit is completed by machine swaging, roller mill, press or other pressure operation, which imparts unlimited flexibility to the unit by crushing and compacting the insulating material employed in and about the heating elements and the unit is ready for use.

As the wiring, connections and control switch for utilizing the unit to obtain desired current variations are conventional, they will not be shown or described in detail.

The accompanying drawings will serve to illustrate several constructions suitable for carrying this invention into effect but it will be understood that no limitation is intended by this showing other than is imposed by the appended claims.

It will be noted that the drawings are on a somewhat enlarged scale and that relative proportions are exaggerated, as believed necessary for clearness of illustration.

In the drawings- Fig. 1 is a perspective view of a short length of a twoice heater element assembly, before being pressure-processed, portions being broken away to show the compact relation of the parts.

Fig. 2 is a cross sectional view of the same on the line s --s of Fig. 1.

Fig. 3 is a similar view showing a three-element heater, and

Fig. 4 is a like View, showing a triangular assembly of the three-heater elements.

Referring now to the drawings, 1 indicates the heating elements, of which there are at least two but a greater number may be employed, if desired. The heating ele-.

ments are ordinarily of conventional form, that is to say, helically wound or otherwise formed of round or ribbon wire, preferably the latter, and provided in the usual manner with suitable terminals for circuit connection and a suitable control switch (not shown).

A multitubular insulator is indicated at 2, which is preformed in one piece, to accommodate a predetermined number of heating elements. The insulator is made of chalky porcelain or like frangible material and, as preformed, is of maximum cross sectional dimensions attained in use. Externally, the insulator is ribbed lengthwise, as indicated at 3, and when the heating elements are entered in the multitubular insulator they snugly fit the bore of the tubular passages that extend through the same and project at either or both ends for the formation of suitable terminals (not shown).

Two, three or more heater elements, assembled in the insulator, are enclosed in closely associated relation, in a metal sheath or jacket 4, filling the greater portion of the bore of the same and leaving comparatively little unoccupied space therein.

The ribs of the insulator contact the bore of the sheath, providing firm anchorage against displacement and this is especially important, particularly when the unit is bent cold on a short radius, to prevent hot spots, shorts, burnouts or other damage.

The unoccupied space Within the sheath is filled with granular or powdered magnesite or like material, as indicated at 5, and when the sheath is closed and sealed about the projecting terminals of the heating elements, in a conventional manner (not shown), the completely assembled unit is ready to be subjected to -a machine pressure operation.

This final step results in crushing the preformed insulator and compacting the pulverized material and the granular magnesite in and about the several heating elements and the unit is ready for use.

Among the important features of the invention may be mentioned the following:

The unit is flexible and may be safely bent cold in any and all directions on a short radius without danger of developing hot spots, shorts, burn-outs or other damage and this ability enables the unit, by cold bending, to be given any and all forms to meet structural use requirements.

The unit has unlimited flexibility and is bendable cold, in any and all directions, on short or long radius, without sufiering damage.

The cross sectional dimensions of the unit are minimized to such an extent, that the extension beyond the diameter of any heating element, is only a small fraction of an inch, which contributes largely to the flexibility of the unit.

The use of the pressure-processing operation to impart flexibility to a non-flexible unit assembly, produces a superior product, at very little cost.

The use of a one piece preformed multitubular insulator, saves cost over individual insulators and saves time and labor in assembling the units What is claimed as the invention is:

1. A flexible electric heating unit assembly, comprising a multitubular insulator preformed of frangible material, a plurality of electric heating elements snugly fitting the tubular portions of the insulator with their terminals projecting beyond the same, a metal sheath closely enclosing the aforesaid assembly, but leaving the terminals exposed, and a filling of granular insulating material in the unoccupied space Within the sheath, the'ends of the sheath being sealed preparatory to a pressure processing step that crushes and compacts the insulating material in and about the heating elements, the unit when completed being flexible and permitting cold bending on any radius without displacing the heating elements.

2'. A flexible electric heating unit assembly, comprising a one piece multitubular insulator of frangible material preformed externally ribbed, a plurality of electric heating elements snugly fitting the tubular portions of the insulator withtheir terminals projecting beyond the same, a metal sheath closely enclosing the aforesaid assembly, but leaving the terminals exposed, and a filling of granula'r insulating material in the unoccupied space within the sheath, the ends of the sheath being sealed preparatory to a pressure processing step that crushes and compacts the insulating material in and about the heating elements, the unit when completed being flexible and permitting cold bending of the same on any radius without displacing the heating elements.

3. An electric heating unit assembly, as defined in claim 2, in which the ribs of the insulator, before the assembly is pressure processed, closely contact the bore of the sheath and center the insulator against displacement therein.

4. An electric heating unit assembly, as defined in claim 2, in which the assembly, before being pressure processed, is rigid throughout and is rendered flexible and bendable in all directions by pressure externally applied to the unit.

5. An electric heating unit assembly, as defined in claim 2, in which at least one element of the assembly, before being pressure processed, is rigid and is rendered flexible and bendable in all directions by pressure externally applied to the unit.

6. An electric heating unit assembly employing more than one heating element, a multitubular insulator for the heating elements, the insulator being temporarily preformed of one rigid piece of frangible material to facilitate assembly of the elements of the unit and being externally ribbed lengthwise thereof, a flexible metallic sheath closely contacting the ribs of the insulator, means for entering granular insulating material to fill the unoccupied space within the sheath and means for pressure processing the assembly to crush the insulator and render the unit flexible and bendable in all directions on any radius.

References Cited in the file of this patent UNITED STATES PATENTS 1,905,232 Kercher et al Apr. 25, 1933 1,927,035 Hicks Sept. 19, 1933 1,982,885 Stupakofi Dec. 4, 1934 2,577,080 Glenn Dec. 4, 1951 2,639,359 Glenn n May 19, 1953 FOREIGN PATENTS 528,718 Great Britain Nov. 5, 1940 503,495 Great Britain Apr. 5, 1939 

